Building insulation is made up of many pieces of insulation aligned in a side-by-side relationship. Typically, each piece of insulation has a body of insulating material and a vapor barrier sheet to which the body of insulating material is attached. The vapor barrier sheet projects beyond the body of insulating material. When a piece of insulation is installed, its vapor barrier sheet is secured to a vapor barrier sheet of an adjacent piece of insulation. Staples are typically used to secure the vapor barrier sheets which project beyond the body of insulating material together. Thus, a joint is formed between the two pieces of insulation after the two vapor barrier sheets are secured together.
A vapor barrier sheet is to keep water vapor in the air out of the body of insulating material, and to provide an aesthetic appearance for the insulation. The vapor barrier sheet covers the body of insulating material and blocks water vapor in the air from entering into the body of insulating material and condensing thereon. Water vapor in the air has a tendency to infiltrate through the joint formed between the two pieces of insulation. This infiltration carries water vapor in the air into the two bodies of insulating material and can create a condensation problem. Such condensation is undesirable because it wets the insulating material causing it to lose its insulating ability.
When staples are used to secure vapor barrier sheets together, care must be exercised in installing the pieces of insulation so that water vapor flow through the joints is kept at a minimum. Additionally, the staples are located between the ends of abutting pieces of insulation, which makes installation cumbersome. Due to the cumbersome nature of the installation and by having to exercise care in installing pieces of insulation, the time and labor required to install the insulation may be substantial. Thus, the cost of installing insulation is relatively high.
The need for staples is eliminated in some insulation by using adhesive to secure vapor barrier sheets together. One example of insulation which uses adhesive and does not require staples is disclosed in U.S Pat. No. 3,121,649. U.S. Pat. No. 3,121,649 discloses a roll of insulation including a vapor barrier disposed along one side of a body of insulation. The vapor barrier extends beyond an edge along the one side of the body of insulation to form a lipped portion of the vapor barrier. A pressure sensitive adhesive strip is bonded to the lipped portion and is covered for shipment and storage by a strip of separation paper. Another pressure sensitive adhesive strip is bonded to a non-lipped portion of the vapor barrier. The non-lipped portion of the vapor barrier is located near another edge along the one side of the body of insulation. The edge along the one side of the body of insulation associated with the non lipped portion of the vapor barrier is located opposite the edge along the one side of the body of insulation associated with the lipped portion of the vapor barrier. This other pressure sensitive adhesive strip is also covered by a strip of separation paper.
To install rolls of insulation, the lipped portion of the vapor barrier of a first roll of insulation is butted against the non-lipped portion of the vapor barrier of a second roll of insulation. The adhesive strip and its separation paper on the lipped portion of the first roll of insulation overlies the adhesive strip and its separation paper on the non-lipped portion of the second roll of insulation. The separation papers on the two rolls of insulation are removed to allow the two adhesive strips to come in contact with each other. A bond between the two adhesive strips is thereby established.
Also, in U.S. Pat. No. 3,121,649, a lipped portion of the vapor barrier projects beyond opposite sides of the body of insulation. Adhesive and separation papers are bonded to each lipped portion. To install rolls of insulation, a lipped portion of one roll of insulation and a lipped portion of another roll of insulation are folded up between the two bodies of insulation. The separation paper on each of the two bodies of insulation is removed to allow the adhesive strip on the lipped portion of one roll of insulation to come in contact with the lipped portion of the other roll of insulation.
A disadvantage in using adhesive strips to secure two bodies of insulation together is that once adjacent adhesive strips come in contact with each other, an installer loses flexibility to make alignment corrections. Another disadvantage is the additional time required of an installer to first remove the separation papers and then bring the adhesive strips in contact with each other. Still another disadvantage is the additional cost associated with producing a body of insulation with an adhesive strip and a strip of separation paper.
Another example of insulation which uses adhesive and does not require staples is disclosed in U.S Pat. No. 3,979,537. U.S. Pat. No. 3,979,537 discloses a roll of insulation in which a vapor barrier extends along one side of a blanket of insulating material. The vapor barrier extends beyond an edge of the blanket to form a tab. The tab is reinforced by either a taping or a folding back of a portion of the tab. To install rolls of insulation, the tabbed edge of a first roll of insulation is butted against a non-tabbed edge of a second roll of insulation. The tab of the first roll overlies a portion of the second roll. A disadvantage in using tape to reinforce tabs is the additional cost associated with producing a blanket of insulating material having tabs reinforced with tape.